the association of bovine osteopontin (opn) gene with milk production traits in iranian holstein bulls

background: the osteopontin (opn) is a highly phosphorylated glycoprotein in numbers of bovine tissues and milk. opn has been reported to be associated with milk production in cattle.objective: the genotype and allelic frequencies for opn and its association with milk production will be evaluated in iranian holstein bulls.  materials and methods: bulls dna (100) was isolated. oligo was used for primer design. polymerase chain reaction was implemented  to amplify a 826 bp fragment and the amplicon was digested by bsri. restricted maximum likelihood (reml) method based on average information algorithm using asrmel programs (version 3.1) was employed to estimate the genetic parameters and variance of components. the association of opn genotypes with milk production traits were analysed by the  least square method as applied in the general linear model (glm) procedure of sas. allele substitution effects were performed by regression analyses.results: allele frequencies of t and c were 0.59±0.03 and 0.41±0.03, respectively. genotype frequencies of tt, ct and cc were 34.69, 48.62, and 16.69, respectively. the chi-square test showed the deviation from hardy-weinberg equilibrium. estimated heritability for milk yield, fat yield and its percent, protein yield and its percent were 0.28±0.0061, 0.21±0.0064, 0.22±0.0086, 0.32±0.0065 and 0.34±0.0096 respectively. allelic substitution effects and differences between genotypes were not significant for milk production traits.conclusions: this study suggested that the c allele frequency of opn was noticeable in iranian proven bull holstein population, but was not associated with milk production traits. however, before being practical for the breeding improvement of iranian holsteins a larger sample size is required.